The present invention relates to impeller pumps and more particularly to the housings and impellers for such pumps.
Impeller pumps are well known and are used for pumping various liquids, such as water and wash liquor in washing machines, for recirculation and to drain. Generally the impeller includes a plurality of vanes carried on a face of an impeller plate, and the entire plate and vanes are rotated by means of a motor via a rotating drive shaft.
In the environment of a clothes washing machine, the liquid flowing through the pump may oftentimes include various solids, such as lint and articles carried in the clothing, for example, coins and jewelry. The confined apace within the pump body, and between the pump body and the impeller, results in the accumulation of these solids, particularly lint, which catches on sharp edges within the pump body, and once caught, act as an accumulation point for additional lint and other solids. This accumulation impedes the movement of the impeller, degrading the performance of the pump, and could ultimately prevent the impeller from rotating, thus terminating operation of the pump. Also, the accumulation of some debris could cause damage to seals within the pump, leading to leakage or failure of the seals.
Impeller pumps, particularly for washing machines, in which the impeller blades are carried on the face of a rotating disc are described, for example in the following U.S. Pat. Nos. 4,355,954; 4,467,627; 4,904,166; 5,009,570; 5,257,901; 6,264,441 and 6,685,428.
Another approach for preventing damage to the pump is disclosed in U.S. Pat. No. 6,857,295, wherein a separate water cavity is provided between the wash tub and the pump inlet, for capturing and holding heavy objects, to prevent them from entering the pump in the first place.
It would be an improvement in the art if an arrangement were provided to overcome the problems caused by lint and other debris in impeller pumps.